Active tension bone and joint stabilization devices

ABSTRACT

Systems and methods of manufacture for bone and joint stabilization devices are described for such devices that are tensioned after anchoring during a medical procedure and remain active in maintaining axial tension for continued compression of the subject anatomy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This filing is a continuation of PCT Application No. PCT/US16/14125,filed Jan. 20, 2016, which claims priority to and/or the benefit of U.S.Provisional Patent Application Nos. 62/107,731, filed Jan. 26, 2015, and62/171,118, filed Jun. 4, 2015, all of which are incorporated byreference herein in their entireties for all purposes.

FIELD

The embodiments described herein are related in the field of surgeryand, more particularly, methods for bone fusion, joint stabilization,and/or fracture fixation surgery.

BACKGROUND

Various devices have been employed in orthopedic surgery for bone fusionand/or joint stabilization. Bone screws, staples and plates have servedas a set of rigid options. Per U.S. Pat. Nos. 4,959,064; 6,656,184;7,833,256; 7,985,222; 8,048,134; 8,449,574 and 8,491,583 and USPPN2006/0264954 some screw-type devices have incorporated tensioningsprings or members. Button-and-suture type devices have provided a moreflexible set of options. U.S. Pat. Nos. 7,235,091, 7,875,057 and8,348,960 offer examples of such device and suitable applicationstherefor.

Various pros-and-cons are associated with the above options. The subjectembodiments seek to address many shortcomings of existing products aselaborated upon below and as may be further appreciated by those withskill in the art.

SUMMARY

Bone and joint stabilization devices are described that are tensionedduring a medical procedure and remain active in maintaining axialtension for continued compression of the subject anatomy during use. Inthe subject embodiments, an orthopedic surgery system comprises anelongate spring member comprising a plurality of beams, each including alateral component free to deflect for stretching the spring memberaxially, and at least one anchoring head adapted to receive the springmember and secure it with a ratcheting interface. Two such heads may beused with one on each side of the elongate spring member. Alternatively,one head may be used along with a foot to anchor an opposite end of thespring member. The anchoring head(s) may retain a low profile whileincorporating two teeth for spring member engagement by virtue of anopposite facing tooth support configuration.

If a distal foot is provided in the system or as part of a sub-assembly,the foot may be adapted to rotate from a position aligned with thespring member to a position transverse to the spring member. In whichcase, the device can be implanted through a minimum-diameter hole orchannel spanning the bone, joint space, or fracture, in the formerconfiguration and then secured or stabilized in the latterconfiguration.

In many cases, it will be desirable to remove the device aftersufficient healing has occurred and the implant is no longer necessary.When the foot is secured to the spring member by filament(s) or cord(one or the other alternatively referred to as a “strand”), the strandmember or members may be cut to facilitate removal of the device.Alternatively, the filament(s) or cord may loop-through the springmember and be held by a rod until the rod is pulled to effect release.Either mechanism can facilitate removal of the device, via minimalincision, once its goal has been accomplished. Total removal may be animportant endpoint for some patients and providers as retained implantscan create adverse reactions.

The rod may include a proximal threaded interface for connection to anextraction tool. The distal end of the rod may be bent or curved with anextension set to interface with the spring member to avoid twistingand/or inadvertent release. In which case, the rod advantageouslycomprise Nitinol that is superelastic (SE) at body temperature (i.e.,having an A_(f) below about 37° C.) so that its distal end may be pulledfrom such location or engagement without fracture.

The anchoring foot may comprise a body with an oval or rectangularplanform shape. Generally, its height and overall size will beminimized, while still maintaining adequate surface area for loadbearing. It may include a transverse groove to act as a pivot with thespring member. It may be relieved over or along one face to accommodateor nest with the elongate member for a reduced crossing profile forinsertion or implantation. The anchor foot may be biased towards atransverse position (e.g., by an integral or a supplemental spring) totransition easily from its axial delivery configuration to its implantedposition against the cortex on the far side. Alternatively, one or morefilaments or pull wires may be employed to accomplish foot rotation.Foot shape may further (or alternatively) assist in this regard.

Whether a pair of head-type anchors are used, or one head anchor and onefoot anchor is used, various features may be included in the system toassist with device removal after implantation. Namely, a sheath may beprovided over the spring member to avoid bone or other tissue ingrowth.The sheath may comprise a biocompatible polymer such as PTFE. A higherstrength polymer such as PEEK or metal hypotube (e.g., Nitinol orStainless Steel) may be selected if additional shear strength is desiredfor the sheath. Especially with the polymer examples, the sheath may betrimmed to length during a medical procedure. Alternatively, a physicianmay select a pre-cut sheath from a group or panel of such items. Inanother approach, the elongate member itself may be polymer coated. Suchcoating may be accomplished by electrostatic (i.e., powder coating),spray or dip coating or as otherwise. The coating may form webbingportions between adjacent beams in the spring.

As for the elongate spring member itself, it preferably includesfeatures for flex, anchor means securing (e.g., setting anchors in placeat a final or near-final treatment position) and ultimate tightening(e.g., by ratcheting adjustment) to desired or selected tensile force bya physician. Such features are integrated in the embodiment(s) shown. Inthese, lateral beams or bars arranged in opposing pairs are connected toeach other at an outer extent. Each such pair may be connected to thenext adjacent pair by a medial connector or bridge.

The beam pairs may each define an aperture or through-hole that canreceive and secure or lock the tooth or pawl of a zip head anchor in agap. In which case, the tooth or teeth in a given anchor head willinterface directly with the beams.

The elongate spring member and its beams advantageously comprise NiTialloy that is superelastic (SE) in use at human body temperature (e.g.,has an A_(f) of about 37° C. or less). Accordingly, the spring membermay be designed and the material heat treated so that it exhibitssuperelasticty when stretched and in use. Otherwise, the NiTi alloy maybe selected or processes so that its potential shape-memory (SMA) effectis used in an embodiment, such that the alloy is heat-activated to turnat least partially phase-transform and tighten (or tighten further) onceemplaced. Alternatively, the spring member may comprise a highperformance or so-called “engineering” polymer such as PEEK. Othermaterials (especially those with high reversible stain potential such asBeta titanium alloy) might be employed as well.

The spring member is advantageously substantially flat. As such, it mayhave an aspect ratio of width to thickness of between about 10 to 1 andabout 30 to 1. Such a form factor minimizes manufacturing complexity andcost in that the spring member may then be cut (e.g., laser cut, waterjet cut or etched) from flat wire, strip or plate. The cut part can bemedia blasted, pickeled and/or electropolished for surface finish.

Methods of system use and manufacture are contemplated herein. In amethod of manufacture for an orthopedic surgery system, stock materialis cut into a linear spring pattern. Per above, such cutting may be bylaser, water jet cutting or etching. Forming an anchor head (e.g., byinjection molding, micromachining, 3D printing or otherwise) adapted tofit and interact with the spring member is likewise contemplated. Theseparts may be provided in packaged combination in a kit to be acquired.Then in an assembly step (i.e., usually carried out by a physician insitu), the spring member is received within at least one anchor headwith a tooth or teeth thereof engaged with through-hoes in the springmember. Advantageously, the through holes are in the spring pattern.This allows for the longest active length of the spring and the prospectof longer axial or linear expansion at lower strains.

In a method of use, an elongate spring member is advanced through a holedrilled through bone or other tissues and set with a distal end distalto a first bone portion and a proximal end proximal to a second boneportion. Then, both ends are secured, with at least one of the endssecured with an anchor including a ratcheting interface. In oneembodiment a foot is used at a distal end to secure that end, and azip-type anchor head used at the proximal end to secure the other end.In another embodiment, two zip heads are used. The spring member is thenpulled through the ratcheting interface (of an anchor head at one orboth sides) tensioning the spring member, typically, with the anchoringmembers or means set in place. The spring member may then be trimmed,cutting off any protruding material. The tensioning and/or trimming maybe performed using an adapted zip-tie gun or it may be done manuallywith hand tools. In any case, no rotary or twisting motion of threads isemployed in tensioning or setting anchor final position. Without therequirement for any twisting or turning of threads to tension (asopposed to existing spring-type screw devices) linear pull on the springmember is instead employed. Accordingly, once tension is set, in somecases the system can be rotated to a preferred position to takeadvantage of flexibility considerations (e.g., as referenced below)without altering or substantially altering device tension.

In one example, each end of the spring member is secured withopposite-facing ratcheting anchor members. In another example, thedistal end is secured with a foot that is initially positioned alignedwith the spring member during advancement through a drill hole, whichthen turns or pivots to secure the distal end. The foot may bespring-loaded for such effect.

As another option, the spring member may be covered by a sheath toprevent tissue ingrowth as mentioned above. The sheath may be advancedover the spring member once it is in place (before proximal anchorplacement). Alternatively, it may be used to support the spring memberfor advancement into place. The sheath may be trimmed to desired lengthbefore or after any such activity, or it may be selected from a panel ofdifferent length pre-trimmed sheaths.

The sheath may be removed as part of an overall orthopedic injurytreatment method with the spring member after healing. Or it may be leftin place, serving the purpose of allowing removal of the spring memberas part of this or these method(s), or as a separate removal proceduremethod.

Likewise, if a foot is included in the system it may be separated fromthe spring member as part of an overall treatment or subsequent removalmethod. This may be accomplished by cutting filament(s) or a cord memberor members holding or tying the foot onto the spring element. A scalpelaccessing from the distal side of the device may be used for thispurpose. The foot could then be removed through a separate smallincision.

Alternatively, the filament(s) or cord may be released by pulling a rodin the case where the member(s) are looped through the spring elementfor securing the foot. The rod may include a threaded proximal interfacefor attaching a threaded cannula thereto from the proximal side of thedevice and pulling the rod, thus facilitating device removal through theoriginal incision without requirement for new incision on the distalside. This represents another advantage over current flexible devices(i.e., button-and-suture systems) and allows safe application inadditional anatomical regions.

The subject devices, kits in which they are included (with or withoutassembly), methods of use (e.g., implantation, during treatment of apatient while mending and/or for system removal) and manufacture(including assembly of the constituent components in vivo or ex vivo)are all included within the scope of the present disclosure. Someaspects of the same are described above, more detailed discussion ispresented in connection with the figures below.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the subject matter set forth herein, both as to itsstructure and operation, may be apparent by study of the accompanyingfigures, in which like reference numerals refer to like parts. Thecomponents in the figures are not necessarily to scale, emphasis insteadbeing placed upon illustrating the principles of the subject matter.Moreover, all illustrations are intended to convey concepts, whererelative sizes, shapes and other detailed attributes may be illustratedschematically rather than literally or precisely.

FIGS. 1A and 1B are side-perspective views of existing orthopedicfixation devices.

FIG. 2 is a front view of an embodiment of the subject device and/orsystem.

FIG. 3A is a side-sectional view of a “zip” type anchor head includingtwo teeth with a spring member received therein; FIG. 3B is a top viewof an optional configuration of the anchor head in FIG. 3A without thespring member in place; FIGS. 3B-3E are side-sectional views of anchorheads as may be incorporated in the system in FIG. 2 or otherwise; FIG.3F is a top view of an optional configuration of the anchor head in FIG.3E.

FIGS. 4A and 4B are side views (each with an inset detail view) ofelongate spring member configurations or embodiments hereof.

FIG. 5A is a side view of a model of a fractured navicular bone; FIG. 5Billustrates the model in FIG. 5A treated using an embodiment of thesubject system.

FIGS. 6A and 6B are partial front and side views, respectively, of adistal anchor embodiment hereof; FIGS. 7A and 7B are partial front andside views, respectively, of a mechanically releasable distal anchorembodiment hereof.

FIGS. 8-14 are anatomical illustrations including various views showingmethods of embodiment system use in orthopedic injury treatmentprocedures including: fixation of a fifth metatarsal fracture (FIG. 8),treating a Lisfranc midfoot ligamentous injury (FIG. 9), fixation of acalcaneal osteotomy for a foot reconstructive procedure (FIG. 10),fixation of a proximal tibio-fibular joint injury (FIGS. 11A and 11B),fixation of a distal tibiofibular syndesmotic injury (FIGS. 12A and12B), fixation of various severity acromio-clavicular joint injuries(FIG. 13), and fixation of a clavicle fracture (FIG. 14).

FIG. 15 is a radiographic image illustrating another embodiment systemin use.

DETAILED DESCRIPTION

Various exemplary embodiments are shown in the figures and furtherdescribed below. Reference is made to these examples in a non-limitingsense, as it should be noted that they are provided to illustrate morebroadly applicable aspects of the devices, systems and methods. Variouschanges may be made to these embodiments and equivalents may besubstituted without departing from the true spirit and scope of thevarious embodiments. In addition, many modifications may be made toadapt a particular situation, material, composition of matter, process,process act(s) or step(s) to the objective(s), spirit or scope of thepresent invention. All such modifications are intended to be within thescope of the claims made herein.

Regarding FIGS. 1A and 1B, these illustrate existing orthopedic fixationsystems. A typical bone screw 10 is shown in FIG. 1A. The bone screwincludes a head 12, shaft 14 and threaded section 14. While the devicehas sufficient strength and stiffness to hold bone fragments togetherafter fracture or osteotomy fixation, compression of the fragments(generally necessary for healing) is typically limited and temporary.Furthermore, a stiff metallic device, like a screw, in a bone can alsocreate severe adverse reactions including but not limited to screwmigration in and/or out of the bone, osteoarthritis, muscle atrophy,nerve damage, pain, bleeding, bone loss, osteonecrosis and/or secondaryfractures due to stress concentration and bone stress at the margins ofthe stiff screw.

A suture-button type device 20 is shown in FIG. 1B. It includes suture22, a proximal button 24 and a distal button 26. In use, the proximalfree ends 28 of the suture are tied-off (manually or a self-lockingfeature may be employed) to secure the device after tightening. Such adevice allows reduction of a joint, limiting widening of the joint alongwith allowing some rotational motion after fixation. It also allowsapplication of some manual (difficult to measure or replicate)compression. However, the device is limited by creep and wear of thesuture which is known to stretch in a biologic environment. Also, thereis no continuous compression beyond what is set at the time ofapplication. Thus, the device can loosen with time, limiting itsapplication to the few joints that have very little motion.

Ultimately, neither of these devices provides continual or continuouscompression to the treatment site. Rather, their tension is set and anymigration or loosening of features results in loss of tension and/orslack.

In contrast, system 100 shown in FIG. 2 is designed for installation,followed by tensioning where that tensioning persists as stored energyin a/the spring member 110. In addition, system 100 can be implementedin a smaller profile where only its elongate spring member 110 need passthrough a drill hole (as opposed to a distal button end 16 and/orthreaded section 16 that cuts deeply into bone).

Spring member 110 is advantageously designed with the hybrid function ofinterfacing with securing the system anchors holding the device andproviding overall tension. As shown in FIG. 2, two identical anchorheads 120 may be used on each side of the spring member. The springmember may be received within an optional sheath 130 as elaborate uponbelow. Optional washers 132 may be interposed as tissue interfaceelements. The washers may be flat or be configured as a “star” type oranother type of lock washers to help prevent rotation among/betweenmembers. Similarly, spikes, splines or studs may be integrated (bymolding, screw-in or otherwise) into the anchor head(s)—typically atunderneath and/or around is lower perimeter.

The zip anchors or anchor heads may be variously configured. They may begenerally square or rectangular in plan form or shape as shown in FIG.2. Alternatively, they may be configured as round or circular bodies.Elliptical and/or other shapes may be employed as well.

The cross section of anchor head 120 shown in FIG. 3A may berepresentative of any such case. However, FIG. 3B provides a top-viewdetail of such an anchor or anchor head embodied in a round or circularform.

In each view, anchor device 120 includes a body 122 with two teeth 124 aand 124 b. The teeth are not stacked vertically as common in other ziptie heads. Rather, the teeth are position on opposite sides of theanchor body and, thus, on opposite sides of the spring member 110 whenit is in place as an assembly. Moreover, the teeth are not directlyacross from one another. Each tooth 124 a, 124 b is staggered andpositioned so an engaged spring member 110 is faced by a support section126.

As such, an engaged spring member lies or abuts against solid material.Tension on the spring member when engaged with the anchor (i.e., pullingon each tooth) is thereby isolated from lateral load/effect of the othertooth so the elongate members or beams 128 a, 128 b support each tooth(optionally) via (essentially) pure tensile or compressive load. Thissimplification of loading may provide additional component strength andhelps enable low-profile component design.

To achieve this goal, the elongate members and tooth surface angles forlocking with a/the spring member(s) are setup at orthogonal angels.Otherwise, the members (i.e., beam/tooth combinations) may be slanted orangled to draw or pull inwardly in stable equilibrium under springmember 110 tension with backing of the spring member by support section126. This result can be achieved (at least to some degree) with theconfiguration shown in FIG. 3A by application of typical draft anglesfor molding to the part.

Regardless, the elongate support members 128 a and 128 b are setup orconfigured as cantilever or cantilevered beam elements with respect tobody 122. A general up/down or opposing orientation or plan for toothand elongate member connection to the body 122 is contemplated. Statedotherwise, one beam carrying a tooth or tooth section is connected tothe body of the zip anchor at or adjacent its bottom (B) and another isconnected at or adjacent to its top (T)—wherein such designation is madefor the anchors 120 in relation to the spring member 110 with which itinterfits. Described in yet another manner, the elongate support membersare each directed inwardly with respect to the outer surfaces of theanchor.

To elaborate, the so-called “bottom” surface is that which the springmember is first fed through (note feed opening (O) and relief chamfer orcutaway (C) provided for such purpose) in use. The “top” surface isacross which the spring member is cut or trimmed after tensioning.Similarly, one tooth (124 a) may be regarded as an/the upper or toptooth, and the other tooth (124 b) regarded as a/the lower or bottomtooth.

An optional radiused or curved rim (R) around the top of the bodyadvantageously provides as an atraumatic interface to the anchor forreduced trauma to surrounding tissues. Such a radius may be applied tocircular body as shown in FIG. 3B and/or other planform shapes as in thesquare-body anchor in FIG. 2 or others. The radius will typically notintersect and/or reduce material of the elongate tooth-support membersso to avoid loss of their strength. In the example shown in FIGS. 3A and3B (taken together, optionally regarded as having a pan or button-headshaped body), the anchor is approximately 0.25 inches in diameter, 0.060inches tall (i.e., as measured between the faces) with a rim radius of0.006 inches.

Another advantageous (but optional) feature concerns the placement ofthe upper tooth within body 122. As shown, the tooth 124 a is configuredand/or otherwise positioned so that when spring member 110 is engagedwith its support surface on the tooth that one full beam width (W), asdiscussed below, is set within the zip anchor body. This relationship ofelements facilitates trimming spring member 110 at a bridge 132 cleanlyor evenly across the zip anchor top (e.g., with flush cutters as aseparate tool or as integrated in a multi-function tensioning andtrimming tool). Moreover, elongate beam member 128 a may include anextension (E) passing beyond its tooth 124 a that bottoms-out against anopposing beam 116 (also discussed below) when engaged with the springmember 110. Such a relationship may be useful for maintaining stabletooth position when the spring member is tensioned.

Yet another option is to terminate the teeth at a sharp or an anglededge (not shown) or include a flat terminal face or passing surface (P)thereto. The latter configuration can protect against scoring orscraping (i.e., liberating particulates) from the teeth when passing thespring member through the anchor body.

In any case, the teeth 124 a, 124 b and apertures or cutouts 112 in thespring member are adapted to work together in a ratchet-type interface.Notably, to interfit with the cutouts 112 in the spring member 110 andinclude two vertically stacked teeth, such a zip anchor (i.e., one withsame-side vertically stacked teeth) would have to be twice as tall as asingle tooth design (i.e., be 2 T vs. 1 T in height). In contrast, anup/down tooth and support beam design shown in FIGS. 3A and/or 3B may beregarded as one-and-a-half times the height (i.e., 1.5 T).

Anchor head 120 is advantageously formed by injection molding inplastic. Biocompatible polyamide (Nylon) or polyethelketone (PEEK) maybe used for such purposes. Other injection moldable anchor variationsare shown in cross section in FIGS. 3C and 3D.

In FIG. 3C, an injection molded anchor head 140 is formed with a plasticbody 122 having a single tooth 124 c. Tooth 124 c pulls inward (i.e.,down and to the left as shown in the drawing) given its overhangingconfiguration at/from its support 128 when engaged with a spring memberunder tension. Such an approach provides a lock in stable equilibrium.Other than presenting a single-tooth variation, the relative dimensionsof elements included in head 140 may match or track with those ofcommercially-available zip tie head(s).

The anchor head 142 in FIG. 3D includes a polymer body 122 and a metaltang or tooth 124 d that functions similarly to that in anchor head 140(in that tooth 124 d pulls down-and-in when under spring membertension). However, this embodiment is dimensioned quite differently thanan off-the-shelf metal tooth zip tie head. For one, an end 144 of tooth124 d is advantageously positioned so that it will abut an opposing wallsupport section 126 of the anchor body 122 when engaged with a springmember (not show). Such an arrangement provides significantly morestrength to the engagement interface. Furthermore, end 144 may be angledor flattened (as shown) to provide an interface that “bites” better intosupport section 126 upon spring member tensioning. Still further,although the tooth may be made of stainless steel (as in existingmetal-tooth zip tie heads), tooth 124 d is more preferably made from SENitinol. SE Nitinol will allow greater flex in a thicker tooth bodywithout plastic deformation. Use of a thicker tooth body may providegreater strength and/or the opportunity to include an extension feature(E) like that shown in the FIG. 3A/3B embodiment. In any case, tooth 124d is advantageously co-molded with body 122 in plastic as in typical ofmetal-tooth zip ties.

FIGS. 3E and 3F illustrate a significantly different type of anchor head146. It is advantageously produced in SE Nitinol, with a tooth 124 eformed in a top piece 122 a mated to a base piece or frame 122 b. Thesemay be attached to one another with a perimeter laser weld bead (WB). Inany case, the base 122 b includes a feed opening (O) and a tooth 124 eformed in the top piece flexes (as indicated by the arrow) to allowinsertion of a spring member. The tooth may overhang the feed opening atits end 144 to ensure one-way operation and further stabilize it when anassociated spring member is in tension.

Tooth 124 e may be defined in top piece 122 a by laser or water jetcutting, etching or machining a kerf 148 with optional stress relieffeatures (R) there through. The same approach may be taken for the feedopening (O) in the base piece. So-manufactured in SE Nitinol, theoverall body 122 may be as little as about 0.020 inches in height withthe top piece being between about 0.005 and about 0.010 inches thick andthe base piece advantageously being between about 0.010 and about 0.015inches thick.

Alternatively, the pieces may be produced in plastic (e.g.,PEEK)—typically with slightly thicker dimensions to account for materialstrength. Plastic pieces may be made by injection molding and/or by thesame techniques used for the Nitinol, without the need for injectionmolding cost and/or associated feature-size, draft angle, etc.requirements or limitations. The plastic body pieces 112 a, 112 b may bejoined or bonded by welding via laser, ultrasonics or otherwise.

Irrespective of the anchor head embodiment selected, the spring membermay be pulled through and locked in tension simultaneously with theanchor head(s). When the spring member(s) is/are made of SE Nitinol,stable positioning of the heads (i.e., anchoring) will typically occurbefore any Stress Induced Martinsite (SIM) formation occurs in thespring member(s). In any case, stable anchor position is achieved withas few as a one or two “clicks” of an anchor's ratcheting interface withthe spring member—especially in cases where the anchors or optionalunderlying washers include pinning or other frictional interfacefeatures such as described above.

Tensioning or preloading the spring member after initial anchoring mayinvolve drawing the spring member through the anchor head(s) by about0.1 inches or up to about 0.25 inches or more depending on the length ofthe spring member and indication to be addressed. The degree ormagnitude of the resulting operative tensioning can be tracked and/orcalculated based on the number of beam pairs (or spring member bridges)pulled through the anchor head(s) ratcheting interface—e.g., by“counting clicks” (after removing system slack for anchoring) inreference to an algebraic formula, look-up table and/or Instructions forUse (IFU) recommendation(s). Otherwise, a standard or customized forcegauge can be employed.

A given spring member is typically tensioned axially such that possiblemigration of its anchor features inward will not leave the spring memberloose or slack. As such, it will continue to deliver “active” tension inuse. This provides a key advantage for optimal healing of a fracture orosteotomy, and for stabilization and healing of a syndesmosis or jointwith limited range of motion.

Various configurations are possible for the spring member (as areanchoring approaches as further discussed below). FIGS. 4A and 4Bprovide side views of alternative spring member configurations. Thevariation 110 a shown in FIG. 4A is like that shown in FIG. 2. Itincludes a plurality of beams 114 where the beams each include a lateralbar component 116 to deflect for stretching the spring member axially.In the spring pattern, lateral bars 116 are provided in opposing pairsjoined to each other at an outer extent connector 118 of each beam. Eachsuch connector may be a curved continuation of each bar or beam member.Each pair of beams is connected to an axially adjacent pair by a medialconnector or bridge 132.

Little to substantially no longitudinal flex or extension occurs at thebridges 132 and/or outer connectors 118 when stretching the overallspring member. Rather, they experience bending loads associated withflexure of the lateral beam elements 114. The pattern of spring member110 b in FIG. 4B is modified somewhat without change in operativeprinciple.

Here the beams are broken into two segments 114 a, 114 b by formation ofcrown sections or segments 134 that are also involved in the bridgesection 132. Such use of the crowns may improve beam segment flexibilityby freeing flexure at junction (J).

The pattern in FIG. 4A may sometimes be preferred, however, in that thecentral flat (F) section offers a clean interface for an anchor headtooth 124. Naturally, hybrid variations (i.e., with anchor-interfacingsections resembling the cutout pattern in FIG. 4A and other sectionswhere no such activity is expected resembling the pattern in FIG. 4B).

In the variations shown, beam width (w) is about 0.008 inches, overallwidth (W) is about 0.09 inches, tooth gap (G) about 0.014 inches.Overall length (L) is about 3 inches. Bridge length (l) is about 0.012inches and bridge width (b) is about 0.012 inches (disregarding radii).Of course, these dimensions are merely exemplary and may be furtherrefined for a selected use, method or application by those with skill inthe art. However, devices configured with the noted dimensions (e.g.,with an overall thickness (T) ranging from about 0.035 to about 0.040inches) offer some notable performance features. Excellent extension andlateral flexibility is observed. As is some asymmetry in the lateralbending potential. The asymmetry can offer advantage in some methodswhere the elongate spring member may be oriented or “clocked”preferentially in one direction (e.g., with overall width (W) orientedfrom noon-to-six o'clock position) or another (e.g., with W orientedfrom three-to-nine o'clock position) in order to offer greaterstabilization and/or mobility around a selected axis or in a selectedplane.

As for use, FIG. 5A illustrates a navicular bone 200 with a fracture202. In FIG. 5B, the bone 200 is shown mended or treated using avariation of the subject system 150. This system 150 differs from system100 in FIG. 2 by inclusion of a distal anchor foot 160 instead of asecond head 120 (although a two-headed approach could be used to treatbone 200). System 150 allows continuous compression of the fracture byminimally invasive means with minimal drilling of bone. Furtherstructural details and details of the foot are discussed below.

With the fracture 202 reduced to an anatomic position, it is subjectedby the device to a compressive force that will continue withoutrelaxation as long as system 150 is tensioned and anchored in place.After it is so-tensioned, the proximal end of the spring member 110 maybe trimmed flush as indicated by the dashed line with end nipper othercutting pliers. Alternatively, a modified version of a cable tie tool orso-called “zip-tie gun” 300 may be used to automatically orsemi-automatically tighten and trim the system.

With respect to anchor foot 160, FIGS. 6A/7A and 6B/7B illustratevarious optional features. Each of the versions employs a foot 160 inthe form of a flat or flattened rectangular body. The footadvantageously includes a transverse groove 162 to serve as a pivot linearound a distal end beam 114 of the spring member. As indicated by thedashed line in FIG. 6B, the height of the foot may also be cut down orrelieved by an amount to define an inset or relief feature (R) toaccommodate the spring member when the foot pivots. Such an inset orrelief feature can reduce the drill size required to install the device.

As shown in FIGS. 6A and 6B, the foot may be held in communication withthe final distal beam of the spring member by filament(s) or a cordstrand 170 that is looped through the bodies (e.g., through a springmember aperture 112 and a channel or through holes—not shown—in thefoot) and tied with a knot 172. As shown in FIG. 6B, the strand may becut with a scalpel 302 or other surgical instrument to release the footfrom the spring member for proximal retrieval of the a majority of thesystem after it has served its purpose.

A more complex attachment arrangement with a pass-through or loopedstrand 174 is illustrated in FIGS. 7A and 7B. Here, the loop is held inplace until rod 180 is pulled free. The rod may include a threadedproximal interface 182 for mating with an extraction cannula 190 topermit remote access. Position of the rod may be maintained by use of anoptional sheath 140 or guides (not shown). Also, rod 180 may include adistal “tail” section 184 that interfaces with a gap 112 in the springmember. This can be employed as a temporary lock that is released whenpulling the rod proximally with sufficient force to plastically,elastically or super-elastically as in the case where the rod comprisesSE Nitinol.

Whether employing such features or not, FIGS. 8-14 further illustratethe subject embodiments (i.e., systems 100 and/or 150) in use. Thesefigures offer a limited representation of medical methods that may beaccomplished given the platform utility offered by the variousembodiments described and others made possible based on this disclosure.

Referring to FIG. 8, it shows fixation of a fifth metatarsal 204meta-diaphyseal fracture (commonly referred to as a “Jones” fracture).The spring member 110 is advanced through a small diameter drill holeformed approximately orthogonal to the fracture 202. If system 150 isused, an attached foot 160 is deployed distally and an anchor head 120is attached proximally with the spring member then tensioned to supplycontinuous compression to the fracture. Such an approach could beapplied to fractures of various orientations in the fifth metatarsal andother tarsal and metatarsal bones. The method may similarly beaccomplished with a system 100 in which the distal anchoring member is ahead 120 (vs. a foot 160).

FIG. 9 illustrates stabilization of a ligamentous “Lisfranc” injurybetween the second metatarsal 206 and medial cuneiform 208. Afterligamentous disruption, the articulation is stabilized by placement ofthe flexible spring member 100 or 150 (with anchor heads 120 or a head120 and distal foot 160, respectively) though a drilled hole. Then witha/the proximal anchor 120 fit over the spring member, spring member 110is tensioned to effect distraction against the distal foot or anchorhead for compression. The system can be placed percutaneously, althoughthe standard is open reduction of the injury.

FIG. 10 illustrates a system 150 with a distal foot 160 deployed and aproximal anchor head 150 set between a spring member 110 compressing acalcaneal osteotomy 210. The system can be employed with a medializing,lateralizing, or closing wedge osteotomy. System 150 (used with orwithout the addition of a sheath 130 and/or washers 132—as is the casewith the other procedures referenced herein) is able to providecontinuous compression, stabilizing the osteotomy, with very littleadded bulk, and small (e.g., 4 mm or less) diameter drill hole forpassing foot 160 and receiving spring member 110 and/or sheath 130.

FIGS. 11A and 11B, illustrate a system 100 or 150 stabilizing a proximaltibio-fibular joint 212 after acute or chronic ligamentous disruption ofthe joint. The selected system can be placed and/or tensioned (to exertappropriate compression on the joint) percutaneously.

FIG. 12 illustrates use of two systems 100 and/or 150 for a tibiofibularsyndesmotic injury 214. Appropriate compression is applied and the twosystems set slightly divergent for maximizing the stability of the jointwhile still allowing a micro-motion environment optimal for ligamenthealing. Such an approach provides many of the advantages of solidscrews and many of the advantages of suture-button type devices, withfew of the disadvantages. The systems can be inserted and tightenedpercutaneously. They can also be placed through a standard (orcustomized) fracture fixation plate in cases of an associated fracturethat requires fixation.

FIG. 13 illustrates use of system 150 with a distal foot 160 andproximal or near-side anchor 120 for fixation of an acromioclavicularinjury 216 with ligamentous disruption. In use, foot 160 is secured byinsertion through a drill hole in the coracoid process 218. Upontensioning, proximal anchor 120 rests against the clavicle cortical bone220.

FIG. 14 illustrates fixation of a clavicle bone 220 with an obliquefracture 202 with a system 150. Here, spring member 110 and foot 160 areinserted through drill hole from the dorsal lateral cortex to plantarmedial. Upon achieving appropriate compression via spring membertensioning with a proximal anchor 120, excess spring member 110 lengthis trimmed off (as it is in the other procedures) prior to closing theaccess incision (again, as in the other procedures).

There are additional indications for the system or device embodimentshereof in settings where continuous compression is necessary or optimaland/or minimally invasive approaches are beneficial. FIG. 15 is aradiographic image providing another such example where a systemembodiment 100 or 150 orthogonally spans a fracture 202 of a fibula 214to allow continuous compression at the fracture site.

As well understood, optimal fracture healing requires reduction of thefracture (i.e., correction of the fracture edges to an anatomicalignment), bone contact, compression of the fragments together, andmechanical stability. The current standard for treatment of many longbone fractures (e.g., tibia, fibula, femur, metatarsals, metacarpals)includes treatment with a lag screw placed orthogonal to the fracturesite, and a plate to stabilize the bones. The lag screw is designed toapply compression at the fracture. However, it does not apply continuouscompression after the device is employed.

In FIG. 15, system 190 includes an elongate spring member 110 thatpasses through a fracture stabilizing plate 192 which is secured withscrews 194. Such an approach allows administration of as much manualcompression as needed (based on stability, bone quality, etc.), andcontinuous compression during fracture healing provided by spring member110. The approach may accelerate bone healing and enhance injuryrecovery. In system 190, separate anchors 120, or a substitute distalfoot 160 (not shown), may be employed for securing spring member 110.Alternatively, the stabilizing plates 192 may include the ratchetingtooth feature(s) 124 otherwise used in an anchor head to secure thespring member.

In this method and others, sufficient compression for fracture healingis achieved by tensioning the spring member to an operative or operatingforce that may be between about 2 to about 5 pounds of force(lbf)—coinciding with the typical maximum force of an “AO” lag screwotherwise used. The subject spring member(s) will provide continuouscompression across a fracture site in this range or higher as selectedby the physician through discrete, incremental, ratcheted, click-typetightening of the spring to aid in expeditious healing.

Variations

In addition to the embodiments disclosed already, still more variationsare within the scope of this description. The subject methods, includingmethods of use and/or manufacture, may be carried out in any order ofthe events which is logically possible, as well as any recited order ofevents. Medical methods may include any of a hospital staffs activitiesassociated with device provision, implant positioning, re-positioning,element (such as an anchor foot) release, retrieval and/or removal ofsome or all of the system components (e.g., it is specificallycontemplate that the foot and/or sheath members may be left in place aspart of a procedure while other components are removed).

Furthermore, where a range of values is provided, it is understood thatevery intervening value, between the upper and lower limit of that rangeand any other stated or intervening value in the stated range isencompassed within the invention. Also, it is contemplated that anyoptional feature of the inventive variations described may be set forthand claimed independently, or in combination with any one or more of thefeatures described herein. Moreover, no limitations from thespecification are intended to be read into any claims, unless thoselimitations are expressly included in the claims.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. In other words, use of the articles allow for “at least one”of the subject items in the description above as well as the claimsbelow. The claims may exclude any optional element. As such, thisstatement is intended to serve as antecedent basis for use of suchexclusive terminology as “solely,” “only” and the like in connectionwith the recitation of claim elements, or use of a “negative”limitation.

Without the use of such exclusive terminology, the term “comprising” inthe claims shall allow for the inclusion of any additional elementirrespective of whether a given number of elements are enumerated in theclaim, or the addition of a feature could be regarded as transformingthe nature of an element set forth in the claims.

The publications discussed herein are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present disclosure isnot entitled to antedate such publication by virtue of prior disclosure.Further, the dates of publication provided may be different from theactual publication dates which may need to be independently confirmed.

The subject matter described herein and in the accompanying figures isdone so with sufficient detail and clarity to permit the inclusion ofclaims, at any time, in means-plus-function format pursuant to 35 U.S.C.section 112, part (f). However, a claim is to be interpreted as invokingthis means-plus-function format only if the phrase “means for” isexplicitly recited in that claim.

While the embodiments are susceptible to various modifications andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that these embodiments are not to be limited to the particularform disclosed, but to the contrary, these embodiments are to cover allmodifications, equivalents, and alternatives falling within the spiritof the disclosure. Furthermore, any features, functions, steps, orelements of the embodiments may be recited in or added to the claims, aswell as negative limitations that define the inventive scope of theclaims by features, functions, steps, or elements that are not withinthat scope.

The invention claimed is:
 1. An orthopedic surgery system comprising: aspring member comprising a NiTi alloy and having an elongate stretchablestructure with two lateral outer extents, the spring member comprising aplurality of beams arranged in pairs, wherein a first beam and a secondbeam of each pair are connected to each other only at the two lateralouter extents such that the first beam opposes the second beam, andwherein each pair of beams is connected to an adjacent pair of beams byonly a medial connector such that gaps are present at the two lateralouter extents between each pair of beams and the adjacent pair of beams;and an anchoring foot rotatable around a pivot located at a distal endof the spring member from a position at least partially aligned with thespring member to a position transverse to the spring member.
 2. Thesystem of claim 1, wherein the pivot comprises a transverse groove inthe anchoring foot interfacing with the distal end of the spring member.3. The system of claim 2, wherein the anchoring foot is secured to thespring member with a cord.
 4. The system of claim 3, wherein the cord isheld by a removable rod.
 5. The system of claim 1, further comprising ananchoring head.
 6. The system of claim 5, wherein the spring member isreceived by the anchoring head.
 7. The system of claim 6, wherein thespring member is engaged by a tooth in the anchoring head.
 8. The systemof claim 6, wherein the spring member is engaged by a single tooth inthe anchoring head, wherein the anchoring head has only the singletooth.
 9. The system of claim 8, wherein the single tooth comprisesmetal.
 10. The system of claim 9, wherein the metal is selected fromstainless steel and a NiTi alloy.
 11. The system of claim 9, wherein theanchoring head includes a feed opening for the spring member and thesingle tooth crosses and overhangs the feed opening.